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Abstract:

A manufacturing apparatus of a preform to be used for an RTM forming,
wherein a layered body consisting of a plurality of layered
reinforcing-fiber base materials to which a fixing agent consisting
primarily of a thermoplastic resin is attached is formed by heating into
a predetermined shape, comprising a forming mold consisting of a first
mold and a second mold facing each other, wherein, only the first mold is
provided with a heating mechanism and a contact face of the second mold
contacting the reinforcing-fiber base material is made of a material
which is less thermally conductive than the first mold.,

Claims:

1.-16. (canceled)

17. A manufacturing apparatus of a preform to be used for an RTM forming,
wherein a layered body consisting of a plurality of layered
reinforcing-fiber base materials to which a fixing agent consisting
primarily of a thermoplastic resin is attached is formed by heating into
a predetermined shape, comprising a forming mold consisting of a first
mold and a second mold facing each other, wherein only the first mold is
provided with a heating mechanism and a contact face of the second mold
contacting the reinforcing-fiber base material is made of a material
which is less thermally conductive than the first mold.

18. The apparatus according to claim 17, wherein the contact face is made
of a material having a thermal conductivity which is equal to or more
than 0.01 W/mK and is equal to or less than 10 W/mK.

19. The apparatus according to claim 17, wherein the contact face is made
of a nonmetallic material having a thickness of at least 5 mm.

20. The apparatus according to claim 17, wherein the first mold is made
of a metallic material.

21. The apparatus according to claim 17, wherein the second mold is a
split mold.

22. The apparatus according to claim 17, wherein the fixing agent has a
glass transition temperature of 50-80.degree. C.

23. The apparatus according to claim 17, wherein the reinforcing-fiber
base material is a carbon fiber base material.

24. A method of manufacturing preforms to be used in RTM forming,
comprising: pressing a layered body consisting of a plurality of layered
reinforcing-fiber base materials to which a fixing agent consisting
primarily of a thermoplastic resin is attached with a forming mold
consisting of a first mold and a second mold facing each other to form a
predetermined shape; heating the predetermined shape to melt the fixing
agent interposed among the reinforcing-fiber base materials only from a
first mold side and a contact face of the second mold contacting the
reinforcing-fiber base material is made of a material which is less
thermally conductive than the first mold so as to suppress the heat from
being conducted to the second mold side, and cooling to solidify the
fixing agent to make the reinforcing-fiber base materials adhere to each
other to maintain a formed shape.

25. The method according to claim 24, wherein the contact face is made of
a material having a thermal conductivity which is equal to or more than
0.01 W/mK and is equal to or less than 10 W/mK.

26. The method according to claim 24, wherein the contact face is made of
a nonmetallic material having a thickness of at least 5 mm.

27. The method according to claim 24, wherein the first mold is made of a
metallic material.

28. The method according to claim 24, wherein the second mold is a split
mold.

29. The method according to claim 24, wherein the fixing agent has a
glass transition temperature of 50-80.degree. C.

30. The method according to claim 24, wherein the cooling is performed
while the layered body is pressed.

31. The method according to claim 24, wherein the reinforcing-fiber base
material is a carbon fiber base material.

32. A preform for RTM forming and manufactured by a method comprising:
pressing a layered body consisting of a plurality of layered
reinforcing-fiber base materials to which a fixing agent consisting
primarily of a thermoplastic resin is attached with a forming mold
consisting of a first mold and a second mold facing each other to form a
predetermined shape; heating the predetermined shape to melt the fixing
agent interposed among the reinforcing-fiber base materials only from a
first mold side and a contact face of the second mold contacting the
reinforcing-fiber base material is made of a material which is less
thermally conductive than the first mold so as to suppress the heat from
being conducted to the second mold side, and cooling to solidify the
fixing agent to make the reinforcing-fiber base materials adhere to each
other to maintain a formed shape.

Description:

TECHNICAL FIELD

[0001] This disclosure relates to manufacturing apparatus and methods of
manufacturing preforms to be used for RTM (Resin Transfer Molding)
forming methods, and preforms manufactured by the methods, and
specifically relates to a technology capable of minimizing the heat
dissipation for heating to form the preform and improving the forming
accuracy.

BACKGROUND

[0002] A conventional manufacturing method of a preform to be used for the
RTM forming method comprises a series of processes as follows, (1)
Layered reinforcing-fiber, base materials are placed in a forming mold
and the forming, mold is closed to form a shape. (2) The forming mold is
heated or preheated to make the base material hot enough to melt the
fixing agent attaching to the base material. (3) The preform is cooled,
to solidify the fixing agent to fix the layers of the base material to
each other while, the forming mold maintains the formed shape. (4) The
preform which has been formed Into a shape is removed from the forming
mold. In such a forming method of preforms, it is usual that metal molds
are used and comprise a lower mold and an upper mold, either of which is
provided with a heating means circulating heat medium or comprising an
electric heater.

[0003] If the shape supposed to be made is comparatively simple, it is
possible that the forming mold comprises only a lower mold and the
layered base material is placed on the lower mold and put in a bagging
film, and the space between the film and the mold is vacuumed to press
the base material through the film by atmospheric pressure to form a
predetermined shape, as disclosed in JP2006-123404-A. However, such a
forming method using the film requires human hands which results in low
productivity and high cost. For such a reason, both upper mold and lower
mold are often used for the forming molds. JP2006-123402-A discloses
upper and lower molds made of aluminum. For example, to form a
complicated three-dimensional shape, JP2009-119701-A discloses a
plurality of movable upper molds.

[0004] However, if the upper and lower molds both are made of metal, the
following problems are expected.

[0005] First, if the lower mold only is provided with the heating means,
heat dissipation toward the upper mold, at the opposite side becomes
greater and, therefore, the lower mold must be heated excessively to keep
the forming temperature constant. Consequently, energy saving is
difficult because heating requires a large amount of energy. Second, if
the lower mold only is provided with the heating means and insulation
material such as foaming material is provided to the upper mold,
dimensional accuracy of the formed preform might decrease because the
insulation material such as foaming material deforms while being pressed
to form the shape. On the other hand, if the upper and lower molds both
are provided with the heating means, it is difficult to make at least one
of the molds a split mold to form a complicated shape.

[0006] Accordingly, with the above-described problems in mind, it could be
helpful to provide manufacturing apparatus and method of manufacturing
preforms, and preforms manufactured by the methods, wherein energy
savings can be achieved, with low heat dissipation and high heating
efficiency, and even a preform formed into a complicated shape can
reliably and easily be manufactured to be used for RTM (Resin Transfer
Molding) forming method with high dimensional accuracy.

SUMMARY

[0007] We provide a manufacturing apparatus of a preform to be used for an
RTM forming, wherein a layered body consisting of a plurality of layered
reinforcing-fiber base materials to which a fixing agent consisting
primarily of a thermoplastic resin is attached is formed by heating into
a predetermined shape, including a forming mold consisting of a first
mold and a second mold facing each other, wherein only the first mold is
provided with a heating mechanism and a contact face of the second mold
contacting the reinforcing-fiber base material is made of a material
which is less thermally conductive than the first mold.

[0008] We also provide a method of manufacturing preforms to be used in
RTM forming, including pressing a layered body consisting of a plurality
of layered reinforcing-fiber base materials to which a fixing agent
consisting primarily of a thermoplastic resin is attached with a forming
mold consisting of a first mold and a second mold facing each other to
form a predetermined shape; heating the predetermined shape to melt the
fixing agent interposed among the reinforcing-fiber base materials only
from a first mold side and a contact face of the second mold contacting
the reinforcing-fiber base material is made of a material which is less
thermally conductive than the first mold so as to suppress the heat from
being conducted to the second mold side, and cooling to solidify the
fixing agent to make the reinforcing-fiber base materials adhere to each
other to maintain a formed shape.

[0009] We further provide a preform for RTM forming and manufactured by a
method including pressing a layered body consisting of a plurality of
layered reinforcing-fiber base materials to which a fixing agent
consisting primarily of a thermoplastic resin is attached with a forming
mold consisting of a first mold and a second mold facing each other to
form a predetermined shape; heating the predetermined shape to melt the
fixing agent interposed among the reinforcing-fiber base materials only
from a first mold side and a contact face of the second mold contacting
the reinforcing-fiber base material, is made of a material which is less
thermally conductive than the first mold so as to suppress the heat from
being conducted to the second mold side, and cooling to solidify the
fixing agent to make the reinforcing-fiber base materials adhere to each
other to maintain a formed shape.

BRIEF EXPLANATION OF THE DRAWINGS

[0010]FIG. 1 is a schematic cross-sectional view of a manufacturing
apparatus of a preform according to the present invention.

[0011] FIG. 2 is a schematic structural view of a test apparatus used in
the examples and comparative examples of the present invention.

[0012]FIG. 3 is a schematic characteristic diagram showing a temperature
distribution in the example of the present invention.

EXPLANATION OF SYMBOLS

[0013] 1: preform manufacturing apparatus

[0014] 2: lower mold as first mold

[0015] 3: upper mold as second mold

[0016] 4: forming mold

[0017] 5: layered body of reinforcing-fiber base material

[0018] 6: heating mechanism

[0019] 7: cooling means

[0020] 8: pressing mechanism

[0021] Q: heat transfer

[0022] l,l1-l7: thickness

[0023] T, T1-T8: temperature on contact face

[0024] λ, λ1-λ7: thermal conductivity

DETAILED DESCRIPTION

[0025] We provide a manufacturing apparatus of preforms to be used for RTM
forming, wherein a layered body consisting of a plurality of layered
reinforcing-fiber base materials to which a fixing agent consisting
primarily of a thermoplastic resin is attached is formed into a
predetermined shape as heated in a forming mold consisting of a first
mold and a second mold which are facing each other, characterized in that
only the first mold is provided with a heating mechanism and a contact
face of the second mold contacting the reinforcing-fiber base material is
made of a material which is less thermally conductive than the first
mold.

[0026] In the manufacturing apparatus, although heating is performed only
from the side of one mold (first mold) of the forming mold which is
provided with the heating mechanism, the heat is less conducted to the
other mold (second mold) and then is less dissipated from the second mold
to the outside because the second mold is made of material less thermally
conductive. As a result, the layered body placed in the forming mold and
is made of reinforcing-fiber base materials to which the fixing agent
consisting primarily of the thermoplastic resin is attached is
efficiently heated to a predetermined temperature with less heat. Saving
energy is enabled by raising the heating efficiency. Further, the
dimensional accuracy in forming preforms can be improved since an
insulation material which tends to deform is not necessary. Furthermore,
because the other mold (second mold) having no heating mechanism can be
configured to a split mold easily, complicated shapes can be formed with
high dimensional accuracy.

[0027] It is preferable that the contact face is made of a material having
a thermal conductivity which is equal to or more than 0.01 W/mK and is
equal to or less than 10 W/mK, and more preferably, made of a material
having a thermal conductivity which is equal to or less than 5 W/mK. It
is preferable that the thermal conductivity of a formation material of
the second mold is low to achieve the above-described high heating
efficiency and excellent energy saving. However, if the thermal
conductivity of the contact face is too low to dissipate the heat from
the inside of the forming mold which is closed and cooled in a process of
solidifying the fixing agent, it might take a long time to cool the
preform. Therefore, it is preferable that the contact face is made of a
material having a thermal conductivity which is equal to or more than
0.01 W/mK, and more preferably, is equal to or more than 0.1 W/mK.

[0028] The formation material of the contact face may be a nonmetallic
material having a thickness of at least 5 mm and is preferably a material
such as a resin which is less thermally conductive and thermally
resistant from a viewpoint of the easy manufacturing. General-purpose
resins such as epoxy resin (thermal conductivity: 0.2-0.4 W/mK), phenolic
resin (thermal conductivity: 0.13-0.25 W/mK), Bakelite resin (thermal
conductivity: 0.33-0.6 W/mK) and PTFE resin (approximately 0.25 W/mK) may
be used. Also other materials such as chemical wood (thermal
conductivity: 0.1-1.8 W/mK) and heat-resistant board material (e.g.
Lossna-board (made by Nikko Kasei Co., Ltd.) thermal conductivity: 0.24
W/mK) may be used. However, the formation material of the contact face is
not limited to the materials exemplified above. Further, the formation
material is required to have a heat resistance large enough to resist the
temperature at which the preform is formed as well as the temperature at
which the thermoplastic resin as the fixing agent is melted.

[0029] A thin nonmetallic material such as a film is not suitable as the
formation material of the contact face. As described above, the forming
process by using bagging films might require human manipulation which
decreases productivity and increases cost. Further, the formation might
not be achieved at the second mold side. Still further, because thin
materials are sensitive to the ambient temperature, the heat conducted
from the first mold provided with the heat source might be dissipated.
Therefore, the heat source should be provided even at the second mold
side. It is preferable that the second mold has a thickness of at least 5
mm.

[0030] In contrast, it is preferable that the first mold is made of a
material having a comparatively high thermal conductivity capable of
conducting the heat to the base material side and is specifically made of
metal. For example, aluminum (thermal conductivity: 204-230 W/mK), carbon
steel (thermal conductivity: 36-53 W/mK), or chrome steel (thermal
conductivity: 22-60 W/mK) may be used. However, the formation material of
the first mold is not specifically limited to the examples described
above.

[0031] As described above, the second mold is not provided with the
heating mechanism and, therefore, can easily be made a split mold. The
split mold can be applied to the forming of a preform into a complicated
shape.

[0032] The material of the reinforcing-fiber base material composing the
layered body is not limited specifically, and may be carbon fiber base
material, glass fiber base material, aramid fiber base material, or
hybrid reinforcing-fiber base material consisting of them. Above all, our
apparatus and methods are specifically effective in the case where the
reinforcing-fiber base material is made of carbon fiber base material
which requires the preform to be formed with a high dimension accuracy in
the RTM forming method.

[0033] As to the reinforcing-fiber base material used in the manufacturing
apparatus, it is preferable that the fixing agent has a glass transition
temperature (Tg) of 50-80° C. If the Tg of the fixing agent is
less than 50° C., the base materials might adhere to each other at
the time of transportation of the base material and decrease
handleability. In contrast, if Tg is more than 80° C., the forming
temperature must be raised so that particularly the second mold might
have to be made of a special material having a high heat resistance.

[0034] It is preferable that the fixing agent attaching to the surface of
the reinforcing-fiber base material primarily consists of a thermoplastic
resin. The thermoplastic resin may be polyamide, polysulfone,
polyetherimide, polyphenylene ether, polyimide, polyamide-imide or
polyvinyl formal, and is not limited in particular.

[0035] If the resin material primarily consists of thermoplastic resin,
productivity improves as does handleability, when the resin material is
sprayed on the reinforcing fiber fabric to be solidified and also when
the layers are fixed after the reinforcing fiber fabric is layered and
transformed into a three-dimensional shape. Besides, what the resin
material primarily consists of is the element which has the greatest
proportion and is called the primary constituent element. That doesn't
exclude instances where the fixing agent contains a thermosetting resin
such as epoxy resin and phenolic resin and, therefore, thermoplastic
resin and/or thermosetting resin can be selected.

[0036] Our manufacturing methods can be used for RTM forming, wherein a
layered body consisting of a plurality of layered reinforcing-fiber base
materials to which a fixing agent consisting primarily of a thermoplastic
resin is attached is pressed with a forming mold consisting of a first
mold and a second mold facing each other to be formed into a
predetermined shape as heated to melt the fixing agent interposed among
the reinforcing-fiber base materials, and then cooled to solidify the
fixing agent to make the reinforcing-fiber base materials adhere to each
other to maintain the formed shape, characterized in that the heating is
performed only from the first mold side and a contact face of the second
mold contacting the reinforcing-fiber base material is made of a material
which is less thermally conductive than the first mold to suppress heat
from being conducted to the second mold side.

[0037] Even in such a manufacturing method, it is preferable that the
contact face is made of a material having a thermal conductivity which is
equal to or more than 0.01 W/mK and is equal to or less than 10 W/mK, and
more preferably, made of a material having a thermal conductivity which
is equal to or less than 5 W/mK.

[0038] Also, it is preferable that the contact face is made of a
nonmetallic material having a thickness of at least 5 mm, as exemplified
above. Further, it is preferable that the first mold is made of a
metallic material as exemplified above. However, for the above-described
reason, it is preferable that the contact face is made of a material
having a thermal conductivity which is equal to or more than 0.01 W/mK,
and more preferably, is equal to or more than 0.1 W/mK.

[0039] Further, it is possible that the second mold which is not provided
with a heating mechanism is a split mold, which can easily be applied to
the forming of a complicated shape with a high dimension accuracy.

[0040] In the manufacturing method, it is possible that the cooling is
performed while the layered body is pressed. If the cooling is performed
while the pressing force is being released, the fixing agent might be
solidified in the released system and, therefore, the dimensional
accuracy of the preform might decrease. Otherwise, the cooling operation
can be performed continuously after the forming operation is performed by
heating so that the production efficiency is improved and the forming
time is shortened.

[0041] Further, our apparatus and methods are specifically effective in
the case where the reinforcing-fiber base material is made of carbon
fiber base material, though the reinforcing-fiber base material is not
limited in particular.

[0042] It is preferable that the fixing agent has a glass transition
temperature (Tg) of 50-80° C.

[0043] Furthermore, we provide preforms manufactured by the
above-described methods. We make it possible that a preform having a high
dimension accuracy is manufactured efficiently with less thermal energy.

[0044] Thus, the base material is heated efficiently as suppressing the
heat dissipation so that the energy saving is achieved by improving
heating efficiency. Further, even in the case where a complicated shape
is to be formed, a desirable preform used for the RTM forming method can
be manufactured surely and easily with a high dimension accuracy and a
high productivity.

[0045] Hereinafter, our apparatus and methods will be explained with
reference to the figures.

[0046]FIG. 1 shows an example of a preform manufacturing apparatus 1. In
preform manufacturing apparatus 1, layered body 5 with a plurality of
layered reinforcing-fiber base materials to which fixing agent consisting
primarily of thermoplastic resin is attached is placed in forming mold 4
consisting of lower mold 2 as a first mold and upper mold 3 as a second
mold facing each other. Only lower mold 2 is provided with heating
mechanism 6 as a flow passageway of heat medium in which hot water or
heated oil circulates. In this example, lower mold 2 is also provided
with cooling device 7 of the air-cooling type or water-cooling type. The
heating mechanism may be provided with a heater, other than the
above-described mechanism in which the heat medium circulates. Cooling
device 7 may cool a preform with compressed air flowing through
through-holes toward the preform and, alternatively, may circulate
coolant water provided in a passageway inside lower mold 2. Upper mold 3
without heating mechanism 6 is configured as a split mold consisting of
divided mold pieces. Upper mold 3 is coupled to pressing mechanism 8
which is capable of moving upper mold 3 with respect to lower mold 2 to
open and close a set of molds and is capable of generating the pressing
force to form layered body 5.

[0047] Layered body 5 is placed in forming mold 4, in which layered body 5
is formed into a predetermined shape by heating with lower mold 2 and
pressing with upper mold 3 through pressing mechanism 8 so that a preform
is manufactured to be used for the RTM forming method. Upper mold 3 of
forming mold 4 is made of a material less thermally conductive than lower
mold 2. More specifically, lower mold 2 may be made of metal such as
aluminum (thermal conductivity at 20° C.: 228 W/mK), aluminum
alloy and steel (thermal conductivity as pure iron at 20° C.; 72.7
W/mK), while upper mold 3 may be made of a thermally-resistant resin such
as phenolic resin (thermal conductivity at 20° C.: 0.233 W/mK).

[0048] In preform manufacturing apparatus 1, layered body 5 is formed into
a predetermined shape by pressing between lower mold 2 and upper mold 3
of forming mold 4, while the fixing agent among the reinforcing-fiber
base materials is melted by heating from the side of lower mold 2 with
heating mechanism 6 and the melted fixing agent is solidified by cooling
with cooling device 7 to fix the reinforcing-fiber base materials to each
other to maintain the formed shape. The heating described above is
performed only from the side of lower mold 2 provided with heating
mechanism 6, and the heat is less conducted to upper mold 3 and then is
less dissipated from upper mold 3 to the outside because upper mold 3 is
made of material less thermally conductive than lower mold 2. As a
result, being placed in forming mold 4, layered body 5 of the
reinforcing-fiber base material to which the fixing agent consisting
primarily of thermoplastic resin is attaching is heated efficiently with
minimum quantity of heat, and then the base materials are fixed with the
solidified fixing agent to each other. Thus, the heating efficiency of
heating mechanism 6 is increased and, therefore, the energy saving can be
achieved by the reduction of energy to be consumed in forming shapes.
Further, dimensional accuracy in forming preforms can be improved since
the above-described insulation material which tends to deform is not
necessary. Furthermore, because upper mold 3 having no heating mechanism
6 can be configured to a split mold as depicted, complicated shapes can
be formed with a high dimension accuracy.

[0049] FIG. 2 shows a test apparatus used to study the desired effects.
Layered body 14 consisting of four carbon fiber fabric 13 is set on lower
mold 12 which has been heated to 100° C. and provided with a
heater as heating mechanism 11 and, then, after closing the mold with
upper mold 15, temperature at each section is measured by thermocouples
16 [(1), (2), (3), (4), (5)] located among the carbon fiber fabrics 13 as
well as at both sides of layered body 14. Upper mold 15 is not provided
with a source of heat. In the example, lower mold 12 is made of aluminum,
and upper mold 15 is made of resin (chemical wood, thermal conductivity:
1.5 W/mK). In the comparative example, lower mold 12 is made of aluminum
(thermal conductivity: 228 W/mK) and even upper mold 15 is made of
aluminum. The mold is closed and then the temporal response of
temperature at each section is measured. Table 1 shows results of the
test.

[0050] As shown in Table 1, even the temperature at section (5) which is
the furthest from the source, of heat arrives at 97.4° C. in the
example where the upper mold is made of resin. That result indicates that
the heat given from the lower mold is not conducted to the less thermally
conductive upper mold and mostly consumed to heat the carbon fiber
fabric. On the other hand, in the comparative example where the upper
mold is made of thermally conductive aluminum, the temperature at section
(3) which is the furthest from the source of heat only arrives at
53.0° C. after 600 seconds and even the temperature at section (1)
which is the closest to the source of heat only increases to 78.1°
C. That result indicates that the heat given from the lower mold is
dispersing to the upper mold side. The preform obtained in the example is
the one with layers firmly fixed to each other. On the other hand,
unmelted fixing agent doesn't fix the interval of the layers sufficiently
in the comparative example. Therefore, the preform loses shape during
transportation and cannot be used for the RTM forming.

EXAMPLES

[0051]FIG. 3 is a schematic characteristic diagram showing a temperature
distribution in an example. FIG. 3 schematically describes the
temperature at each section in a condition where layered body 5
(consisting of five layers) of the reinforcing-fiber base material is
interposed between lower mold 2 as first mold and upper mold 3 as second
mold and heat transfer Q is generated from lower mold 2 to upper mold 3.
T(T1-T8) indicates each temperature (° C.) of contact
face at each section, l(l1-l7) indicates each thickness (m) of
each layer, and λ(λ1-λ7) indicates each
thermal conductivity (W/mK) of each material.

[0052] In FIG. 3, if it is assumed that lower mold 2, upper mold 3 and
layers of layered body 5 are regarded as plane parallel plates coherent
to each other, the contact thermal resistance on the contact faces
between the layers is ignored and heat transfer Q is caused based on a
steady heat conduction (T1 is constant and T8 is constant),
transferred heat quantity q (W/m2) can be expressed by the following
formula (1).

q = ( T 1 - T 8 ) n = 1 8 l n λ n
( 1 ) ##EQU00001##

[0053] Here, T2 to T7 can be expressed by the following formula (2) (where
2≦i≦7).

[0060] As apparent from Tables 2 and 4, in the case where upper mold 3
located far from the source of heat is made of thermally conductive
aluminum, or carbon steel, the difference of temperatures is smaller in
upper mold 3 and, therefore, the temperature on the surface of upper mold
3 decreases. Particularly in the case where the reinforcing-fiber base
material is made of less thermally conductive PAN-based carbon fiber or
glass fiber, heat conduction from lower mold 2 becomes smaller and
therefore, the temperature on the surface of upper mold 3 decreases
greatly.

[0061] However, in the case where upper mold 3 is replaced by the one made
of less thermally conductive resin, heat transfer is limited inside upper
mold 3 and, therefore, the difference of temperature is greater so that
the temperature decrease in each layer of the reinforcing-fiber base
material can be reduced even if the reinforcing-fiber base material is
made of less thermally conductive PAN-based carbon fiber or glass fiber.

[0062] According to the above-described calculation results, if upper mold
3 is made of thermally conductive material, it is likely in a real
preform manufacturing apparatus that the heat transfer is progressively
performed inside upper mold 3 and, therefore, it takes a long time to
increase the temperature of each layer of the reinforcing-fiber base
material near upper mold 3. On the other hand, if upper mold 3 is made of
less thermally conductive material, the heat transfer is limited inside
upper mold 3 and, therefore, the temperature near upper mold 3 is
prevented from decreasing so that the temperature of each layer of the
reinforcing-fiber base material is increased rapidly even if the
reinforcing-fiber base material is made of less thermally conductive
PAN-based carbon fiber.

INDUSTRIAL APPLICATIONS

[0063] The manufacturing apparatus and manufacturing method of a preform
is applicable to any use where preforms are required to be formed with a
high accuracy as saving energy for an RTM forming method.